The present invention relates to a numeric-control machine tool for turning and hobbing mechanical parts.
In order to produce mechanical parts which require both turning and hobbing it is currently necessary to use two separate machine tools, i.e., a lathe, whereby it is possible to turn, mill and drill the part, and a gear hobbing machine solely for hobbing.
In practice, the mechanical part is generally subjected mainly to turning, in preparation for hobbing, on the lathe, and is then removed from the lathe and placed on the main mandrel of the gear hobbing machine.
In many cases, after hobbing it is necessary to perform further machining with machine tools, for example to deburr and/or chamfer the set of teeth, to form axial and/or radial external grooves, radial threads, cams, etcetera. In such cases, it is necessary to perform an additional transfer of the mechanical part from the gear hobbing machine to another machine tool.
The operation for transferring the mechanical parts from one machine tool to the other significantly affects the time requirements and therefore the overall costs of machining.
Moreover, the part must be positioned on each machine tool with high precision in order to comply with design tolerances.
Transfer of the mechanical part from one machine tool to another is even more complicated to perform when the subsequent machining must be performed in relation to a specific angular position of the part about its own axis, in a technique known as phase matching.
Modern machining lines include specifically provided robotized pick-and-place units, even of the numeric-control type, which transfer the parts from one machine tool to another.
However, these devices are extremely complicated and significantly affect the investment costs of the system.
Another problem arising from the need to use a lathe and a gear hobbing machine is certainly constituted by the overall purchase cost of these machine tools and by the space required in the workplace, which are an additional burden in terms of investment and running costs.
Another problem that arises from the combined use of a lathe and of a gear hobbing machine is the need to provide for a storage area for the parts to be hobbed between the lathe and the gear hobbing machine.